Dont tell me you have never found a leaky glass one or dont you hi-pot them?
How and why would you suggest gettering them (-;
Carl
KM1H
----- Original Message -----
From: "Fuqua, Bill L" <wlfuqu00@uky.edu>
To: "Carl" <km1h@jeremy.mv.com>; <amps@contesting.com>
Sent: Sunday, November 06, 2011 6:55 PM
Subject: RE: [Amps] Gettering 3-500 Tubes
Why we don't we need to getter vacuum variable capacitors?
73
bill wa4lav
________________________________________
From: Carl [km1h@jeremy.mv.com]
Sent: Sunday, November 06, 2011 4:56 PM
To: Fuqua, Bill L; amps@contesting.com
Subject: Re: [Amps] Gettering 3-500 Tubes
----- Original Message -----
From: "Fuqua, Bill L" <wlfuqu00@uky.edu>
To: <amps@contesting.com>
Sent: Sunday, November 06, 2011 1:09 AM
Subject: Re: [Amps] Gettering 3-500 Tubes
I have quite a collection of power tubes. Many built 50 or more years ago.
I rarely find
gassy tubes. I have trouble with the idea that air leaks thru the envelope
of glass tubes.
I suspect that if a small amount of air does get into the vacuum it is from
a virtual leak.
These are due to tiny gas pockets or bubbles in seals or defects in the
internal metal parts.
I is a common problem in research high vacuum systems. The gas does not
come from the outside
thru the glass but from a flaw in the glass or other material that holds a
small amount of gas after
the tube is pumped out.
If a 60 or 70 yea old large power tube still has a hard vacuum I think it
is unlikely that air is leaking thru
the glass.
73
Bill wa4lav
Youre lucky, there is no other explanation.
>From 204A's and 211's thru 304TL, 6C21, 4-1000A, etc Ive seen many with air
contamination still NIB. Other than selling the desired ones to audiophools
they are only good to display.
How or why they leaked I have no idea, there is no sign of physical abuse.
Carl
KM1H
________________________________________
From: amps-bounces@contesting.com [amps-bounces@contesting.com] On Behalf Of
rbethman [rbethman@comcast.net]
Sent: Saturday, November 05, 2011 7:08 PM
To: amps@contesting.com
Cc: R Johnson
Subject: Re: [Amps] Gettering 3-500 Tubes
I wouldn't be concerned with "Gettering".
*IF* there is air leakage into the tubes, they will show a cloudy gassy
look.
Go ahead and try them as they are after you've gotten the rest sorted out.
*IF* it was me, I'd replace the capacitors in the HV section. 20 years
is a long time, and Heath didn't always use the "High" end parts.
Bob - N0DGN
On 11/4/2011 12:05 AM, R Johnson wrote:
> I have just been given an old SB-220. It has been sitting in an attic for
> 20+ years.
>
> I have removed the tubes and have been bringing the voltage up slowly
> to reform the filter caps. When I get to 120V in and the caps aren't
> steaming
> and/or blowing smoke I'll be ready to check it with the tubes installed.
>
> I know that the need 3-500's will need to be "Gettered" to remove any gas
> diffusion
> thru the metal to glass seals on the tube.
>
> I read a procedure on (probably) on this list on how to do it.
> Now that I need it, I can't find it.
>
> Does anyone remember this thread within the last 3 or 4 months ???
> If not,can any recommend how to cook these tubes in ???
>
> TNX es 73
> Bob, K1VU
>
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
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